Radio frequency switch



Sept. 29, 1942. p EHLERT r 2,297,207

RADIO FREQUENCY SWITCH Filed Oct. 20, 1938 INVENTORS PAUL EH 7' RUDOLFPE'HR/SCH D ERIC/l C EN wmH L/ ATTORNEY Patented Sept. 29, 19422,291,207 7 anmo FREQUENCY swrrcn Paul Ehlert, Rudolf Pehrisch, andErich Clasen,

Berlin, Germany; vested in the Alien Property Custodian ApplicationOctober 20, 1938, Serial No. 236,026 a I In Germany October 1, 1937 g 8Claims.

This invention relates to a new and novel radio frequency switch whichis especially adapted for short wave circuits.

An object of this invention is to eliminate the defect of imperfect,insumcient contact in transmitters used on both long and short wavecircuits, and is accomplished by the arrangement of a plurality of wiresprings, cage-fashion, around a circular conductor, each of thesesprings insuring safe and perfect and uniform contact.

The types of switch known in the earlier art are more or lessunserviceable for high-frequency, especially short waves, when largecurrents and high voltages are used. The underlying reason resides inthe special conditions surrounding high frequency work. Where switchesintended to handle high-frequency currents are concerned, one problem isto make the path of the current as short and linear as possible in orderthat the inductance of the path may be minimized. The other problem isto prevent the field from becoming particularly intense at some localpoint as a result of dissymmetric distribution for this is liable tolead to a dissymmetric current load of the contacts or even sparking atundesired places, for this is likely to lead to the destruction of thecontacts. At the same time, the contact-making area should be as largeas feasible and should be safe and be dependable at a maximum number ofpoints.

All of these requirements are fulfilled in excellent manner by theswitch of this invention in which, interiorly of a hollow body a seriesor bank of contact springs being interconnected and serving as a switchcontact are distributed over its circumference in such a uniform mannerthat there results an opening into which a metallic rod forming thecooperating contact and shiftable in axial sense may be inserted so thatit will cause the contact springs to spread apart.

The chief advantage of the invention resides in the symmetricarrangement, for the disposition of a great number of individual springsinsures a practically symmetric field. The contact is resolved ordivided into a series of paralleled and symmetrically disposed solitarycontact points, and the contact conductance of these may be renderedalike since each of the springs is adjustable separately. The contactingof each spring may be insured practically in one point, while thecontact pressure can be made very high. The path'over which the currentis made to flow is comparatively short and straight. These merits of theinvention become particularly manifest when the hollow body has acylindrical hole and when the springs form a circular opening into.which a cylindrical rod is shifted.

The line may be connected with the rod, for instance, by means of aflexible and movable strand or cable or the like. However, a preferableplan is to mount two or more hollow cylinders comprising symmetricallymounted springs are superposed coaxially and insulated from one anotherthat the rod will pass through all of the hollow cylinders so that, byaxial shifting, one bank of springs is united with the other. The leadsor circuit elements to be connected together are then united each with adistinct bank of springs.

An exemplified embodiment of the invention is shown in Fig. 1, thisbeing a top view after removal of the upper closing lid E. Fig. 2 is across-sectional view. The embodiment shows a step condenser for radiofrequency. In a metallic case of cylindrical shape G are disposed threesimilarly shaped metal squares H, H, H" with cylindrical bores 0 so asto be placed in superposition and coaxial andinsulated from one another.Each of the squares has an annular groove on its top face into which arefitted the ends of a row of hook-shaped springs F. The ends of thesprings are anchored in position by means of annularly recessed contactplates fitted thereon as indicated at P, while the latter, in turn, areheld in position by a flange-like clamp or pressure plate D fitted onthem and screwed fast on the four corners of the square. The springs Fare preferably made of cylindrical copper wire. Shiftable in the boresis the metallic switch column S of cylindrical shape. The lower end ofthe said rod-like column or pillar is tapered conically so that the rodwhen pushed into the bore causes the springs to spread apartsymmetrically in the presence of sliding friction until they haveassumed the operating position. In this latter position the bottom endsof these springs bear firmly against the outer edge of the milled recessA formed in the interior of the bore 0. The springs may be individuallyadjusted in a simple manner so that the contact pressure of all thesprings becomes of like amount. Each of the three groups of banks ofsprings is united with a coat of the condenser group; and each of thecondenser groups, in turn, comprises four paralleled condensers disposedin circular symmetry. In other words, the upper stage contains the fourcondensers designated by Ki, K2, K3, K4; the second stage the condensersKl, K2, K3, K4, and the lowermost stage the condensers Kl", K2", K3",K4". The switch shaft S is constantly united with the upper group ofsprings and thus with the top stage or group of condensers. Each of thecondensers, say, Kl comprises a series system of several individualcondensers, in other words, of several .coats separated by insulation.The innermost coat is formed by bending over a projecting flap or lug ofthe contact plate P so as to be positioned parallel to the cylinder axisand as a result very perfect contact is established between thecondenser and the switch springs F. The outer coat of each condenser isunited with the casing G in that a screw R inside the casing compressesthe condenser packet in the direction towards the cylinder axis. Thesescrews establish not only conductive connection between the outer coatsand the casing, but they also hold the entire stage inside the casing.If desired, in order to improve the conductive connection, a separateconnecting lead may be provided be tween the outer condenser coat andthe casing.

The outer casing is grounded, while the inner coat of the uppermoststage condenser is fixedly and conductively connected with a terminal Kfitted into the closing plate or lid E consisting of insulationmaterial. The said terminal could, of course, consist also of a metallicring which would then serve at the same time to afford a hold for theswitch pillar Orshaft.

In case a relatively high initial capacity is desired, it will beadvantageous to provide four stages or tiers, and of these theungrounded coats of the first two stages are permanently in conductingrelation with the switch shaft' S and thus with the terminal K, while inthe two bottom condenser groups the switch column may be introduced atwill.

The arrangement as shown insures a strictly symmetric and concentricpositioning of the wires with a very low resultant inductance; at thesame time it represents a very compact efliciently organizedconstruction unit.

The motion of the rod-shaped switch pillar S may be eifected in anydesired manner at all either from a remote or from a neighboring controlor operating point.

A plurality of step condensers of this kind may be disposed adjacent orbchind one another, and they may be fitted with joint switching andnotching means. When disposed in superposition, a common switch shaftmay be provided which has insulation pieces at intermediate points. Inthis case, the arrangement could also be modified in this way that theshaft of each 'step condenser does not represent a straight line,

but a part of a circular ring, with the various condensers being mountedone behind the other upon the circular ring, while the switch pillarpassed through all of them is also a circular rmg.

Moreover, the arrangement could, of course, also be modified in thismanner that the rodshaped switch pillar is immobilized, while the hollowcylinders carrying the springs are shifted.

Finally, the following modified embodiment is feasible in which, uponthe exterior of a cylinder, a row of contact springs is disposed incircular symmetry in such a fashion that the springs form a circle whileabove this circle is shifted a metallic axially shiftable hollowcylinder in such a way that it compresses the springs.

What is claimed is:

1. A short wave radio frequency switch .for

switching a group of electrical units in circuit comprising a metalliccasing member, an insulating cover secured to said casing, a metallicslidable switch member arranged to slide through said insulating cover,a plurality of metallic blocks having a central bore with radiallyextending slots, a plurality of conductively interconnected contactsprings arranged in said radially extending slots, said blocks arrangedin a tier within said casing and serving with said springs as switchcontact means equally distributed over the periphery of said metallicslidable switch member so that there remains an opening in which saidmetallic member acts as the cooperating contact to close said switch,said contact springs arranged in a plurality of superimposed groups,said group of electrical units being interposed between said casing andeach group of contact springs, said slidable memberarranged to connecteach group of said electrical units together in parallel as it is movedthrough said cover.

2. A short wave radio frequency switch comprising a cylindrical metalliccasing member, an insulating cover secured to one end of and completelyenclosing said casing member, a rod-like metallic switch member slidablyarranged to pass through the axis of said insulating cover, a pluralityof metallic blocks having a central bore and radially extending slots, aplurality of contact springs serving as switch contact means 10- catedin said slots, said contact springs arranged so that when said switchmember is telescoped within said springs the switch is closed.

3. In means for switching a plurality of electrical units into acircuit, a metallic casing mem her, an insulating cover secured tosaid'casing member, a plurality of metallic hollow bodies havingapertures therein supported by said casing, one of the end faces of saidhollow bodies having formed thereon a plurality of radially extendingslots, a plurality of hook-shaped springs secured in said slots, aplurality of pressure plates secured to one end of said hollow bodiesfor retaining said hook-shaped springs thereto, and a metallic slidableswitch member arranged to slide through said insulating cover, saidelectrical units being interposed between said hollow bodies and saidcasing member, the slidable switch member arranged to connect saidelectrical units together by telescoping one of its ends through andcontacting said springs.

4. In means for switching a plurality of electrical units into acircuit, a circular metallic casing member, an insulating cover securedto said casing member, a plurality of metallic hollow bodies havingapertures therein supported by said casing, one ofthe end faces of saidhollow bodies having formed thereon a plurality of radially extendingslots, a plurality of bookshaped springs secured in said slots, aplurality of pressure plates secured to one end of said hollow bodiesfor retaining said hook shaped springs thereto, a plurality of bentcontact plates interposed between said hollow bodies and said springmembers, a metallic slidable switch member arranged to slide throughsaid insulating cover, said electrical units being interposed betweensaid bent contact plates and said casing member, the slidable switchmember arranged to connect said electrical units together by telescopingone of its ends through and contacting said springs.

5. In means for switching a plurality of electrical units into acircuit, a metallis cas ing member, an insulating cover secured to saidcasing member, a plurality of groups of superimposed rectilinear contactmembers having apertures therein and supported by said casing, eachgroup of contact members arranged in a tier, one of the end faces ofsaid rectilinear contact members having formed thereon a plurality ofradially extending slots, a pinrality of hook-shaped springs secured insaid slots, a plurality of pressure plates secured to one end of saidcontact members for retaining said hookshaped springs thereto, ametallic slidable switch member arranged to slide through saidinsulating cover, said electrical units being interposed between saidsuperimposed rectilinear contact members and said casing member, theslidable switch member arranged to connect each group of superimposedrectilinear contact members together in parallel.

6. In means for switching a plurality of electrical units into acircuit, a metallic casing member, an insulating cover secured to saidcasing member, a plurality of hollow bodies having a cylindrical boresupported within said casing member, a metallic slidable switch member,one of the end faces of said hollow bodies having formed thereon aplurality of radially extending slots, a plurality of hook-shapedsprings located in said slots, a plurality of pressure plates secured toone end face of said hollow bodies to retain said springs in said slots,said metallic slidable switch member arranged to be capable oftelescoping within said hollow bodies to connect said electrical unitstogether in parallel.

7. A short wave radio frequency switch for switching electrical unitscomprising a cylindrical metallic casing member having an opening at oneend thereof, an insulating cover having an aperture therein and securedto the opening in said casing member, a rod-like metallic switch memberslidably arranged to pass through the aperture in said insulating cover,a plurality of metallic blocks having a central bore and radiallyextending slots, a plurality of contact springs serving as switchcontact means located in said slots, and a clamp plate secured to saidcentral bore for retaining said contact springs thereto, said contactsprings and metallic blocks being arranged so that when said switchmember is telescoped within said springs the switch is closed.

8. A short wave radio frequency switch for switching electrical unitscomprising a cylindrical metallic casing member having an opening at oneend thereof, an insulating cover having an aperture therein and securedto the opening in said casing member, a rod-like metallic switch memberslidably arranged to pass through the aperture in said insulating cover,a plurality of rectilinear metallic blocks serving as a central abutmentmember for retaining a plurality of electrical units which areinterposed between said casing and said rectilinear blocks, a pluralityof contact springs serving as switch contact means located within saidrectilinear metallic blocks, said contact springs arranged so that whensaid switch member is telescoped within said contact springs theelectrical units are connected together in parallel.

PAUL EHLERT. RUDOLF PEI-IRISCH. ERICH CLASEN.

